The office of a former New Mexico governor says he and Google chairman Eric Schmidt will head to North Korea this week on a "private humanitarian mission."

Bill Richardson says the trip is linked to North Korea's arrest last year and planned prosecution of a US citizen of Korean descent.

The US State Department has voiced concerns about the trip, saying it was ill-timed in the wake of Pyongyang's widely condemned rocket launch last month.

The former US ambassador to the UN has been to North Korea a number of times in the past 20 years and has been involved in negotiating the release of US citizens detained in the isolated state.

Mr Richardson's office says he will hold a press conference at the airport in Beijing on Thursday, adding that no journalists would be accompanying the delegation.

Spokespeople for both Mr Richardson and Mr Schmidt did not immediately respond to requests from AFP for further details about the trip.

On Friday Mr Richardson said he hoped the trip would be "positive". He also dismissed US concerns about the mission, saying the trip had already been postponed once at Washington's request.

Mr Richardson has stressed that he and Schmidt will be travelling as private citizens, representing neither the US Government nor Google.

The former governor said the son of the detained American had contacted him and asked for his assistance.

Kenneth Bae, also identified as Pae Jun-Ho, was arrested in November as he entered the north-eastern port city of Rason near North Korea's border with Russia and China.

North Korea's official Korean Central News Agency (KCNA) said the Korean-American tourist had admitted committing a crime against the state.

Pyongyang has in the past agreed to hand over detainees to high-profile delegations led by the likes of former US president Bill Clinton, and some observers suggested it may have requested Mr Schmidt's participation in this case.

The former New Mexico governor said while a meeting with North Korean leader Kim Jong-Un was "very doubtful," he expected to meet with several senior officials.

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